Seal mechanism

Abstract

To provide a seal mechanism that can suppress oil film shortage and exhibit excellent sealability on a seal mechanism that includes a seal member made of an elastomer.SOLUTION: A seal mechanism 50 includes: a seal member 30 fitted to one of the stationary side structure 10 and movable side structure 20; and a metallic surface 22 included in the other, where the seal member 30 comes into slide contact with the metallic surface 22, the seal member 30 is an elastic body, a lubricant 40 is interposed between the seal member 30 and the metallic surface 22, and a plurality of dimples 25 are provided in a region of the metallic surface 22 with which the seal member 30 comes into slide contact.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sealing mechanism.

Background Art

[0002] Between various fixed-side structures and movable-side structures, a sealing mechanism is formed by attaching a sealing member to one of them and causing the sealing member to be in sliding contact with the metal surface of the other. As an example, in machines such as pumps and ships, a rotating shaft or a rotating shaft (propeller shaft), which is a movable-side structure, is rotatably mounted in a through hole provided in a machine body or a ship body, which is a fixed-side structure. In order to seal between the body and the rotating shaft or the like, a sealing member is attached to the body side, and a form can be cited in which the tip of the sealing member is in sliding contact with the metal surface of the rotating shaft or the like.

[0003] Here, "sealing" is a general term for parts, materials, and operations that prevent leakage of liquids or gases to the outside and intrusion of rainwater, dust, etc. into the inside in machines and devices, and a mechanism that performs sealing with a sealing member is a "sealing mechanism". In addition, "sealing" is also defined in Japanese Industrial Standard JIS B 0116 "Terms for Packings and Gaskets". Packings applied to moving parts include oil seals, U-packings, O-rings, etc., and gaskets applied to non-moving parts include metal gaskets, O-rings, etc.

[0004] Generally, mirror finishing such as cutting, grinding, and polishing is performed on the metal surface of the fixed-side structure or the movable-side structure with which the sealing member is in sliding contact in order to reduce friction with the sealing member. However, on a mirror-finished metal surface, regardless of the magnitude of the surface roughness, recesses in the cross-sectional shape of the unevenness are likely to be formed in a sharp, streak-like shape. When a metal sealing member slides on this machined surface with lubricating oil supplied, the lubricating oil flows into the tip acute angle portion of the recess by capillary action due to the surface pressure during sliding, and there is a problem that oil film breakage occurs due to the escape of the lubricating oil. This problem also exists in cross grinding.

[0005] From the above, instead of mirror-polishing the metal surface, a technique has been proposed in which the metal surface is subjected to dimple processing to form a large number of dimples, and lubricating oil is retained in the dimples to prevent oil film breakdown. And a sealing mechanism in which a metal sealing member is in sliding contact with a metal surface provided with a large number of dimples is known.

[0006] By the way, recently, there is also a sealing mechanism provided with a sealing member made of an elastic body typified by rubber instead of a metal sealing member. However, even when the sealing member is an elastic body, a sealing mechanism in which a sealing member made of an elastic body is in sliding contact with a mirror-polished metal surface is known, and the above-mentioned problem of oil film breakdown is inherent, similar to the case of a metal sealing member.

[0007] Here, Patent Document 1 proposes a sealing mechanism in which a mounting piece portion of a sealing member having a V-shaped cross section is inserted into a mounting groove portion of a fixed-side object, and a pressing piece portion of the sealing member is pressed against a movable-side object.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] According to the sealing mechanism described in Patent Document 1, it is said that the sealing member can be easily mounted in the mounting groove portion. However, there is no disclosure of means for suppressing oil film breakdown in the sealing mechanism provided with a sealing member made of an elastic body, that is, the above-mentioned problem.

[0010] An object of the present invention is to provide a sealing mechanism provided with a sealing member made of an elastic body, which can suppress oil film breakdown and has excellent sealing performance.

Means for Solving the Problem

[0011] To achieve the above object, one aspect of the sealing mechanism according to the present invention is a sealing mechanism in which a sealing member is attached to one of a fixed-side structure and a movable-side structure, the other has a metal surface, and the sealing member is slidably contactable with the metal surface, wherein the sealing member is an elastic body, a lubricating oil is interposed between the sealing member and the metal surface, and a plurality of dimples are provided in a region of the metal surface where the sealing member slidably contacts.

[0012] According to this aspect, since the sealing member made of an elastic body is slidably contactable with a metal surface provided with a plurality of dimples in a region where the sealing member slidably contacts, oil film breakage can be effectively suppressed. And the sealing mechanism in which the sealing member made of an elastic body slidably contacts a metal surface provided with dimples is a novel sealing mechanism that has not existed conventionally. In this novel sealing mechanism as well, the inventors have confirmed that it has excellent sealing performance.

[0013] Due to the unevenness of the dimples, the surface area of the metal surface increases, and the heat dissipation performance is improved, so that the cooling efficiency of the metal surface is improved, and the temperature rise of various devices provided with the sealing mechanism can be suppressed. In addition, when the dimples are minute micro dimples, the oil film retention can be enhanced by the labyrinth effect of a large number of micro dimples, and the occurrence of ringing is suppressed, so that the sliding contact operation becomes smoother, which is preferable.

[0014] Here, "the sealing member is slidably contactable with the metal surface" includes both a mode in which a sealing mechanism is formed by the sealing member slidably contacting the metal surface and a mode in which a sealing mechanism is formed by a lubricating oil interposing between the metal surface and the sealing member. In addition, the "dimple" is, for example, a micro (microscopic) dimple having a size on the order of micro, etc. As a dimple processing method for processing such micro dimples on the metal surface of the outer periphery of the rotating shaft, for example, shot blasting, WPC (Wide Peening and cleaning registered trademark) processing, etching processing, and electric discharge machining can be mentioned. In addition, there are various types of lubricating oils (greases) depending on the combination (formulation) of a base oil, a thickener, and a solid lubricant.

[0015] In addition, another aspect of the seal mechanism according to the present invention is characterized in that the elastic body is a seal rubber.

[0016] According to this aspect, since the elastic body is a seal rubber, which is a material generally applied in a seal mechanism provided with a seal member made of the elastic body, good seal performance can be guaranteed. Here, examples of the seal rubber include nitrile rubber (NBR) and fluororubber (FKM).

[0017] In addition, another aspect of the seal mechanism according to the present invention is characterized in that the friction between the seal member and the metal surface is reduced by the seepage of the lubricating oil contained in the dimple.

[0018] According to this aspect, the friction between the seal member and the metal surface is reduced by the seepage of the lubricant contained in the dimple, resulting in a seal mechanism with a high friction reduction effect. More specifically, the lubricating oil in the dimple has no escape path, and a reaction force against the pressing force from the sliding contact seal member acts to float the seal member, suppressing or eliminating the direct contact between the seal member and the metal surface, thereby reducing the wear and friction coefficient between the seal member and the metal surface.

[0019] In addition, in another aspect of the seal mechanism according to the present invention, The dimple is a minute concave that is curved and sunken, and is characterized in that the inlet diameter is in the range of φ5 μm to φ100 μm and the depth is in the range of 0.5 μm to 3 μm.

[0020] According to this aspect, since the dimple, which is a minute concave with a curved shape, has an inlet diameter in the range of φ5 μm to φ100 μm and a depth in the range of 0.5 μm to 3 μm, it is possible to ensure a high friction reduction effect between the seal member and the metal surface and a high oil film retention property within the concave of the dimple.

[0021] Moreover, another aspect of the seal mechanism according to the present invention is characterized in that both the fixed-side structure and the movable-side structure are components of a shield tunneling machine.

[0022] According to this aspect, since both the fixed-side structure and the movable-side structure are components of a shield tunneling machine, a seal mechanism having a high sealing property against earth and sand, groundwater, etc. can be applied to various locations in the shield tunneling machine. Here, examples of the seal mechanism in a shield tunneling machine include a bearing seal between the tunneling machine body and the cutter head rotating device, an earth and sand seal between the cutter head (or cutter spoke) and the copy cutter, and the like.

[0023] Moreover, another aspect of the seal mechanism according to the present invention is characterized in that the fixed-side structure is the main body of a foundation construction machine, and the movable-side structure is the rotating shaft of the foundation construction machine.

[0024] According to this aspect, since the fixed-side structure is the main body of the foundation construction machine and the movable-side structure is the rotating shaft of the foundation construction machine, it is possible to effectively prevent earth and sand, groundwater, etc. from entering the inside of the main body of the foundation construction machine. Here, the foundation construction machine includes a boring machine (swivel device, hydraulic device, etc.) used for ground (geological) investigation and pile construction, a submersible pump, and the like.

Advantages of the Invention

[0025] According to the sealing mechanism of the present invention, it is possible to suppress oil film breakage and provide a sealing mechanism having excellent sealing performance.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0027] Hereinafter, the sealing mechanism according to the embodiment will be described with reference to the accompanying drawings. In the present specification and the drawings, substantially the same components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0028] [Sealing Mechanism According to the Embodiment] First, with reference to FIGS. 1 and 2, an example of the sealing mechanism according to the embodiment will be described. Here, FIG. 1 is a schematic diagram showing an example of the sealing mechanism according to the embodiment, and FIG. 2 is a schematic diagram for explaining the operation of an example of the sealing mechanism according to the embodiment.

[0029] The sealing mechanism 50 shown in Fig. 1 includes a plurality (two in the illustrated example) of seal members 30 attached to the main body 10 (an example of a fixed-side structure) that constitutes a foundation construction machine, a rotating shaft 20 (an example of a movable-side structure) rotatably disposed in the X1 direction inside the main body 10, and a lubricating oil 40 filled between the two seal members 30 and the metal surface 22 of the rotating shaft 20. A part of the seal member 30 is configured to be slidably in contact with the metal surface 22 of the rotating shaft 20, and the sliding contact of the two seal members 30 with the metal surface 22 and the lubricating oil 40 filled therebetween prevent the intrusion of earth and sand, water, dust, etc. from the outside of the main body to the inside of the main body.

[0030] Here, examples of foundation construction machines include boring machines (swivel devices, hydraulic devices, etc.) used for geological surveys and pile construction, and submersible pumps. Note that the application target of the sealing mechanism according to the embodiment is not limited to foundation construction machines, and various devices that require a sealing mechanism, such as ships and shield tunneling machines, are applicable. For example, in a ship, a sealing mechanism is applied between the main body, which is a fixed-side structure, and a rotating shaft (propeller shaft), which is a movable-side structure.

[0031] On the other hand, sealing mechanisms are applied to various locations in a shield tunneling machine, including a bearing seal between the tunneling machine main body and the cutter head rotating device, an earth and sand seal between the cutter head (or cutter spoke) and the copy cutter, a floating seal in the rotary joint between the cutter head and the rotating device, an earth and sand seal in the roller cutter, a seal in the mud conveying and discharging slide device, a seal in the emergency water stop device in the tail section, a seal in the folding mechanism of the folding tunneling machine, and various other sealing locations.

[0032] Also, in the illustrated example, the seal member 30 is attached to the fixed-side structure 10, but depending on the application target of the sealing mechanism, a form in which the seal member is attached to the movable-side structure and is slidably in contact with the metal surface of the fixed-side structure may be applied.

[0033] On the inner wall surface of the through hole 12 provided in the body 10, for example, an annular seal member mounting portion 14 is provided in the circumferential direction thereof. In the seal member mounting portion 14, a plurality (two in the illustrated example) of annular fixing grooves 16 are provided at intervals in the axial direction thereof, and a part of the annular seal member 30 is fixed to each fixing groove 16.

[0034] The seal member 30 is a seal rubber (an example of an elastic body). Specifically, nitrile rubber (NBR), fluororubber (FKM), urethane rubber (U), silicone rubber (VMQ), ethylene propylene rubber (EPDM), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), acrylic rubber (ACM), etc. are applicable.

[0035] The seal member 30 has a key portion 31 fitted into the fixing groove 16, an arm portion 32 extending while bending from the key portion 31, and a lip portion 33 located at the tip of the arm portion 32. The lip portion 33 is in slidable contact with the metal surface 22 of the rotating shaft 20 facing it.

[0036] As shown in FIG. 2, the bent arm portion 32 is biased in the Y1 direction in which it opens itself. Due to the biasing force acting from this arm portion 32, the lip portion 33 contacts the metal surface 22 of the rotating shaft 20 in a posture of applying a pressing force P1.

[0037] Between two annular seal members 30 attached in the axial direction to the annular seal member attachment portion 14, lubricating oil 40 is filled through a filling hole 18 provided in the main body 10. Here, there are various types of lubricating oil 40, which are combinations (formulations) of base oil, thickener, and solid lubricant. For example, base oils include mineral oil, polyalphaolefin, diester, polyol ester, polyglycol, diphenyl ether, silicone, fluorine oil, etc. On the other hand, thickeners include soap-based ones such as calcium soap and lithium soap, and non-soap-based ones such as bentonite and silica. On the other hand, solid lubricants include molybdenum disulfide, graphite, PTFE (polytetrafluoroethylene, Teflon (registered trademark)), MCA (melamine cyanurate, melamine cyanurate flame retardant), boron nitride, metal powders such as copper and nickel, etc.

[0038] The metal rotating shaft 20 has a cylindrical or cylindrical shape, and a plurality (a large number) of dimples 25 are provided in a region (sliding contact region 23) of the metal surface 22 where the lip portion 33 of the seal member 30 makes sliding contact.

[0039] The dimples 25 are, for example, micro-order micro (micro) dimples. Examples of dimple processing methods for processing such micro dimples 25 on the metal surface 22 of the rotating shaft 20 include shot blasting, WPC processing, etching processing, and electrical discharge machining.

[0040] The dimples 25 are minute recesses recessed in a curved shape. For example, as shown in FIG. 2, the inlet diameter φ is set in the range of 5 μm to 100 μm, and the depth h is set in the range of 0.5 μm to 3 μm. By providing a large number of dimples 25 with such dimensions on the metal surface 22, a high friction reduction effect between the rotating rotating shaft 20 and the seal member 30 and high oil film retention in the recesses of the dimples 25 can be ensured.

[0041] As shown in Fig. 2, the lubricating oil 40 within the dimple 25 has no escape route, and a reaction force P2 against the pressing force P1 from the lip portion 33 of the sealing member 30 in sliding contact acts, causing the lip portion 33 to float in the Y2 direction. As a result, the lubricating oil 40 contained in the dimple 25 oozes out to the outside of the dimple 25 (the lip portion 33 side), suppressing or eliminating the direct contact between the lip portion 33 and the metal surface 22 of the rotating shaft 20, and reducing the wear and friction coefficient between the lip portion 33 of the sealing member 30 and the metal surface 22 of the rotating shaft 20.

[0042] Also, due to the unevenness of the numerous dimples 25, the surface area of the metal surface 22 of the rotating shaft 20 increases, and the heat dissipation performance is improved. As a result, the cooling efficiency of the metal surface 22 is improved, and the temperature rise of the construction machinery equipped with the sealing mechanism 50 can be suppressed.

[0043] Moreover, since the dimples 25 are minute microdimples, the retention of the oil film can be enhanced by the labyrinth effect of the numerous microdimples 25. Since ringing does not occur, the sliding contact operation becomes even smoother.

[0044] Furthermore, even if fine dust or the like enters from the outside between the lip portion 33 and the metal surface 22 of the rotating shaft 20, the fine dust or the like can be collected within the dimple 25, thus ensuring a smooth and long-time rotation operation of the rotating shaft 20.

[0045] [Verification Experiment on Sealing Performance and Its Results] The inventors conducted a verification experiment to verify the sealing performance of the sealing mechanism 50 shown in Fig. 1. Here, Fig. 3 is a diagram for explaining the experimental apparatus applied in the verification experiment for verifying the sealing performance.

[0046] This experiment is a ball-on-disk friction and wear test (experiment). As shown in Fig. 3, a ball test piece is pressed into a disk test piece placed on a stage rotating in the Z2 direction with a vertical load in the vertically downward Z1 direction to bring about pressing contact, and it is a friction and wear test method that generates a frictional force in the Z3 direction between the two. Since a plane and a sphere are in contact, the contact area is small, and stable contact can be maintained at a high surface pressure. Also, since the disk rotates, the circumferential velocity can be changed according to the rotation radius and the number of rotations, and a friction and wear test can be carried out at a wide range of sliding velocities of about 1 to 1000 mm / sec.

[0047] Since it is known that the sealing performance (sealing performance between metal-metal) is improved at the contact surface between a metal surface subjected to dimple processing and a metallic sealing member, it was verified in this experiment whether the sealing performance (sealing performance between metal-rubber) can be similarly improved at the contact surface between a metal surface subjected to dimple processing and a rubber seal.

[0048] Here, the size of the dimples on the metal surface is such that the average diameter is 160 μm (77 to 336 μm), the average depth is 9 μm (6.1 to 12.4 μm), and innumerable such dimples were formed. Also, the tip (sliding part) of the ball (rubber seal) held by the ball holder was made into a circular protrusion with a diameter of φ5 mm.

[0049] Also, as the lubricating oil (grease), trade name: New-SL PS70 (Daiso Nichimori Co., Ltd.) was used. The appearance is white, the base oil is a synthetic oil, the solid lubricant is a white solid lubricant, the thickener is lithium, the consistency is 280, and the operating temperature range of -30 to 150°C was used.

[0050] Furthermore, 0.2 g of SiC particles (particle size D50 is 11.5 ± 0.5 μm, particle size Max is ≦ 32 μm) as fine particle dust was added to 2 g of this grease and thoroughly mixed, and 0.05 g of grease containing SiC was applied to one disk.

[0051] In this experiment, a disk with a mirror-finished surface (without fine particle dust) was used as Comparative Example 1, a disk with a mirror-finished surface and fine particle dust applied was used as Comparative Example 2, a disk with a dimpled surface (without fine particle dust) was used as Example 1, and a disk with a dimpled surface and fine particle dust applied was used as Example 2. The verification experiment results are shown in Fig. 4.

[0052] Fig. 4 is a graph showing the relationship between the sliding distance and the friction coefficient for Comparative Examples 1 and 2 and Examples 1 and 2. From Fig. 4, by comparing Comparative Example 1 and Example 1, it can be seen that the friction coefficient is smaller for the dimpled surface than for the mirror finish.

[0053] Also, by comparing Comparative Example 2 and Example 2, it can be seen that even when there is dust on the surface, the friction coefficient is smaller for the dimpled surface than for the mirror finish.

[0054] From the above, it has been verified that excellent sealing performance is also achieved regarding the sealing performance between the rubber seal and the dimpled metal surface.

[0055] Incidentally, when comparing Examples 1 and 2, it can be inferred that the reason the friction coefficient gradually decreases is that the familiarity improves with sliding from the initially poor familiarity state.

[0056] Also, in the comparison with Comparative Examples 1 and 2 and the comparison between Examples 1 and 2, the friction coefficient tends to be smaller for the one with dust at the initial stage of the experiment. It can be inferred that this may be because the dust (SiC) exerts a bearing effect at the initial stage of the experiment.

[0057] Also, in the comparison with Examples 1 and 2, the magnitudes of the friction coefficient are reversed at a sliding distance of 400 m. It can be inferred that this may be because the dust gradually bites into the rubber with sliding and the bearing effect is eliminated.

[0058] Furthermore, other embodiments may be possible in which other components are combined with the configurations and the like described in the above embodiments, and the present invention is not limited to the configurations shown here. In this regard, it can be changed without departing from the spirit of the present invention and can be appropriately determined according to the application form.

Explanation of Signs

[0059] 10: Fixed-side structure (main body of foundation construction machine, main body) 12: Through hole 14: Seal member attachment part 16: Fixed groove 18: Filling hole 20: Movable-side structure (rotating shaft of foundation construction machine, rotating shaft) 22: Metal surface 23: Sliding contact area 25: Dimple (micro dimple) 30: Seal member 31: Key part 32: Arm part 33: Lip part 40: Lubricating oil (grease) 50: Seal mechanism P1: Pressing force P2: Reaction force

Claims

1. A seal mechanism in which a seal member is attached to one of a fixed structure and a movable structure, and the other has a metal surface on which the seal member is in sliding contact, The sealing member is an elastic body, a lubricant is interposed between the sealing member and the metal surface; A sealing mechanism characterized in that a plurality of dimples are provided on the metal surface in an area with which the sealing member slides.

2. 2. The sealing mechanism according to claim 1, wherein the elastic body is a sealing rubber.

3. 3. The seal mechanism according to claim 2, wherein the friction between the seal member and the metal surface is reduced by seeping out of the lubricating oil contained in the dimples.

4. 3. The sealing mechanism according to claim 2, wherein the dimple is a minute recess that is curved and depressed, the entrance diameter of which is in the range of φ5 μm to φ100 μm, and the depth of which is in the range of 0.5 μm to 3 μm.

5. 5. The sealing mechanism according to claim 1, wherein both the fixed structure and the movable structure are components of a shield tunneling machine.

6. the fixed structure is a main body of a foundation construction machine, 5. The sealing mechanism according to claim 1, wherein the movable structure is a rotating shaft of the foundation construction machine.

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